1. Field of the Invention
This invention pertains to the field of holders for surface mount components or computer chips. More particularly, this invention pertains to a snap-on lid for a JEDEC tray for computer chips.
2. Description of the Prior Art
In the prior art, the extreme sensitivity of surface mount components (SMCs or, more commonly, computer chips) to electrostatic discharge (static electricity) and electromagnetic interference, as well as poor handling and soldering defects due to high moisture content is well known. This sensitivity becomes particularly important in the transportation or handling of computer chips. In order to transport computer chips from one place to another, several types of apparatus have been designed to shield computer chips from static electricity, electromagnetic interference, poor handling and high moisture.
Representative of these prior art attempts are U.S. Pat. Nos. 5,115,912; 5,109,981; 5,064,064; 5,058,743; 5,038,248; 5,024,329; 4,886,163; 4,767,003; 4,706,161; 4,702,371; 4,666,545; 4,595,096; 4,528,222; 4,448,306; and 4,426,675.
More particularly, with respect to tray type holders, U.S. Pat. No. 4,767,003 discloses a stack of trays for holding electronic components. Similarly, U.S. Pat. Nos. 5,115,912 and 5,109,981 disclose electric component carriers with downwardly extending legs which are formed to engage a frame.
However, these prior art attempts have not been as economical and as widely accepted as the JEDEC (Joint Electronic Device Engineering Counsel) trays. JEDEC trays are injection molded. They are designed and built in compliance with JEDEC standard outline dimensions. Tray markings contain a vendor information block, revision level and a device information block. The corner adjacent to the markings is notched for identifying the component pin-1 orientation. The number of components per tray varies with the size of the components. JEDEC trays have locating and hold-down tabs designed for automatic assembly equipment. JEDEC trays are stackable and are used as transport carriers during the component manufacturing processes. JEDEC trays meet many SMC protective and handling requirements for manufacturers and customers.
SMC manufacturers package 4 to 6 trays per box depending on the part quantity. Extra trays are used to hold down the parts in the top tray and protect the leads of the parts in the bottom tray (see FIGS. 1 and 2). In the prior art, manufacturers have been known to use as covers plastic or cardboard sheets tied or strapped to a stack of JEDEC trays with rubber bands, wire ties, cable ties, Velcro.RTM. strapping or plastic strapping prior to placing the trays into the shipping boxes.
However, when a customer of a distributor orders a portion of the contents of a factory sealed box, the distributor frequently is forced to obtain an empty JEDEC tray, at an expense of approximately five dollars, to use as a top lid for the order. This can easily double the packaging expense for small orders, such as when a first JEDEC tray is used as a carrier and the second JEDEC tray is used as a lid.